"This observation is our most surprising and exciting finding," says Michael Detmar, MD, of the MGH Cutaneous Biology Research Center, the study's senior author. "It's a new twist to the 'seed and soil' hypothesis, which postulates that distinct cancer types preferentially metastasize to organs that are optimally suited for them. Our results indicate that the 'seeds' can actively modify the 'soil' and prepare it for later metastatic arrival."
While it is now accepted that tumors can stimulate development of their own blood supply, a process called angiogenesis, similar growth of new lymphatic vessels was not suspected until 2001. At that time Detmar and his colleagues showed that human breast tumors implanted into mice induce the growth of lymphatic vessels and that lymphangiogenesis plays a key role in tumors' spread to lymph nodes. It had previously been believed that tumors had no functioning lymphatic vessels. The 2001 study focused on VEGF-C, the first factor identified to promote lymphatic vessel growth, and subsequent research has identified another lymphatic factor called VEGF-D, which also is active in the spread of cancer.
While VEGF-A had been believed to promote the development of new blood vessels only, recent research at the MGH and elsewhere found that it also induced proliferation of lymphatic tissue and vessels in laboratory and animal
Contact: Sue McGreevey
Massachusetts General Hospital